There is currently no internationally accepted definition to specify the notion of a city. This way, each country defines its concept of a city, based on certain geographical, historical or administrative considerations. In many countries, the criterion of demographic size is applied to identify small cities with other urban categories in the urban system. In this regard, the UN recommends as a criterion for defining the city a human settlement with a minimum threshold of 2,000 inhabitants. For the delimitation of cities, beyond the quantitative criteria for population numbers, several states of the world have also used qualitative criteria based on the functions they perform or the environment's relationship to the city.